The present invention relates to an animal collar which includes a device to reduce predation by the subject animal by emitting a signal audible to its intended prey. In particular, the collar is intended to reduce predation by domestic cats.
Domestic cats are known to have a serious impact on bird populations. Worldwide, cats may have been involved in the extinction of more bird species than any other cause except habitat destruction and they are also contributing to the endangerment of populations of other rare small mammals. In Britain alone, domestic cats now number 7.2 million and are thought to kill at least 75 million birds annually. In Australia, the countries 21 million feral and domestic cats are believed to be responsible for killing 3 million animals per year including 67 native bird species and in the US, the 60 million domestic cats are estimated to kill more than 1.4 billion birds each year.
Although cats make affectionate pets, many domestic cats hunt as effectively as wild predators. However, domestic cats are thought to represent a greater problem than wild predators for the following reasons: Firstly, domestic casts are protected from disease, natural predation and competition, factors which control numbers of wild predators. Secondly, domestic cats have a dependable supply of food provided by humans and are, therefore, not influenced by changes in populations of prey. This means that cats can continue to hunt even rare species. Thirdly, unlike many native predators, cat densities are poorly limited or not limited at all by territoriality. Fourthly, unlike some predators, a cat""s desire to hunt is not suppressed by having an adequate supply of supplemental food. Therefore, a cat""s motivation to hunt remains strong even when fed regularly.
Despite being responsible for killing numerous birds and small animals, cats can also perform a useful function as companion pets. They also hunt pests and vermin which tend to feed at night, for example rats and mice.
It is therefore desired to reduce the number of bird and small animal deaths caused by cats during the day without reducing a cat""s effectiveness in hunting and killing vermin and pests, such as rats and mice, which generally feed at night.
The following terms used herein are intended to be interpreted in the manner indicated below:
xe2x80x9csubject animalxe2x80x9d is an animal e.g. a domestic cat, carrying a device according to the present invention.
xe2x80x9caudiblexe2x80x9d is used to mean capable of being heard by at least one species of prey of the subject animal. Sounds which are audible to certain animals or birds may be outside of the hearing range of human beings.
xe2x80x9cPredationxe2x80x9d is used to mean the killing of or injury to prey by the subject animal.
According to a first aspect of the invention there is provided a sonic device capable of being carried by a predatory animal, the device including means for emitting a sonic signal for alerting prey to the animal""s presence.
The sonic signal may be intermittent or it may be continuous.
In embodiments where the sonic signal is intermittent, the delay between the emission of the intermittent sonic signals i.e. the periods when no signal is emitted, may be variable. Preferably the delay between emissions is between 0.5 and 600 seconds, more preferably between 1 and 60 seconds and most preferably between 5 and 10 seconds.
The duration of the emitted sonic signal i.e. the period when the signal is being emitted, may also be variable. The emitted sonic signal preferably lasts between 0.05 and 10000 milli-seconds, more preferably between 100 and 1000 milli-seconds and most preferably between 200 and 300 milli-seconds. The signal is preferably audible to a wide variety of potential prey of the subject animal. In a preferred embodiment the frequency of the emitted signal is between 300 and 8000 hertz. The device preferably includes means to vary the frequency of the emitted signal. More preferably, the device further includes means for generating a frequency modulated signal in which the frequency is continuously variable in a predetermined manner.
Embodiments of the invention in which the sonic signal is continuous may be useful for subject animals whose prey includes fast moving animals such as bats. In these situations, the sonic signal may be an ultrasonic signal i.e. a sonic signal having a frequency greater than about 20 kHz. For the purposes of this invention, the term xe2x80x9csonic signalxe2x80x9d is intended to include signals having a frequency in the ultrasound region (i.e. signals having a frequency greater than about 20 kHz).
The device is preferably carried by the animal via an attachment means, more preferably by a collar.
The device is preferably lightweight and more preferably small enough to be worn by the animal on eg. a collar without interfering with the animal""s normal behaviour, other than its predatory behaviour.
Since the device may be worn permanently by the animal, it should preferably have a rugged construction capable of withstanding vibration and small impacts without impairing the performance of the device and more preferably it should be waterproof. By permanently it is meant either the lifetime of the animal or the lifetime of the device.
In a preferred embodiment, the device is housed in a housing. The housing may be constructed such that it is possible to obtain access to the device eg. the housing is a two-part construction wherein the two parts are releasably coupled to each other. Alternatively it may be constructed such that it is not possible to obtain access to the device without breaking the housing. That is to say the housing and device may be constructed as a disposable unit.
The device may be battery powered. The battery lifetime is preferably 1 year or more. In order to achieve this long lifetime the components of the device are preferably low power consumption components. To improve battery lifetime, the device may include one or more solar panels and a battery capable of being recharged by energy converted from solar energy by the or each of the solar panels.
The distance at which the signal is audible to a species of prey of the subject animal is preferably 3 meters or more.
The sonic signal may mimic an alarm or distress call of a particular species of prey. This type of signal is useful for protecting specific endangered or rare animals or birds which are at risk from attack by the subject animal. Alternatively, the sonic signal may be a complex synthesised sound. By this it is meant that the alarm or distress call is electronically generated. Where the signal is an alarm or distress call of a particular animal or bird, or a complex synthesised sound, it may be recorded and stored in the device, for example in a memory chip. The stored alarm or distress call or complex synthesised sound may be capable of being repeatedly emitted as the sonic signal of the device.
The emitted sonic signal preferably does not cause distress to the subject animal wearing the device or interfere with its normal behaviour, except of course its predatory behaviour.
In a preferred embodiment the subject animal is a domestic cat. Domestic cats spend part of their time within a domestic environment e.g. in its owner""s home. To prevent the sonic signal of the device becoming a nuisance within the domestic environment, the device may be deactivated when the animal e.g. cat is within a predetermined area. To achieve this, the device preferably includes switching means which is capable of activating the device outside of the predetermined area and deactivating it when the animal is within the predetermined area.
The switching means may be operable as the animal passes through a predetermined opening of the domestic environment e.g. a cat flap. Such switching means may include a Hall Effect sensor within the device which is sensitive to a particular magnetic field generated in the proximity of the cat flap.
As an alternative to the switching means being operable as the animal e.g. a cat passes through a predetermined opening of the domestic environment e.g. a cat flap, the switching means may be sensitive to an inductive loop transmitter system wherein an inductive loop may be wired around the domestic environment and is driven electronically or simply by a loop amplifier powered e.g. by mains electrical supply.
A further alternative switching means includes an RF signal receiver responsive to RF signals transmitted from an RF transmitter located within the domestic environment. The device is deactivated when the RF receiver of the device carried by the animal comes within range of the RF signals transmitted by the transmitter and the device is activated when the RF receiver no longer receives the RF signals. The RF transmitter is preferably mains powered, but it could alternatively be battery powered, battery and mains powered, solar powered or powered by any other suitable means. The RF transmitter may be portable such that it may be connected to a suitable mains electrical supply within different predetermined areas. The transmitting range of the RF transmitter may be variable such that it can cover differently sized domestic environments.
A yet further alternative switching means includes an ultrasonic signal receiver responsive to ultrasonic signals such that the switching means may activate or deactivate the device in response to the received ultrasonic signals.
The RF receiver in the device may be modified so that it can receive radio broadcasts from an alternative or a second source, different to the RF transmitter which is in or near to the domestic environment. The RF signals broadcast by the second source are preferably capable of being converted into sonic signals emitted by the device. For example, a specific animal or bird distress or alarm call, or a series of these, may be broadcast as an RF signal by the second source and received by the RF receiver in the device. The received RF signal from the second source is then converted into the specific distress or alarm call, which is emitted by the device either in place of the predetermined sonic signal or in addition to the predetermined sonic signal. This modified device is particularly advantageous in situations where a specific rare animal or bird is introduced or reintroduced into an area e.g. a small island. The alarm or distress call of this animal or bird can be encoded in the form of an RF signal which is transmitted throughout the area, whereupon any predators in the area who are carrying a device according to this preferred embodiment of the invention will receive the broadcast. The device will then process the broadcasted RF signal and emit a sonic signal corresponding to that encoded in the RF transmission, thereby reducing predation by the subject animal of the specific animal or bird, whose alarm or distress call was encoded in the RF transmission. Alarm or distress calls of more than one animal or bird may be encoded and broadcast.
To enable the subject animals e.g. cats to continue to hunt pests and vermin at night, the device preferably includes an optical switch. This activates the device during daylight hours and deactivates it during the night. It is known that in bright sunlight the light intensity is about 20,000 lux. This falls to less than about 10 lux during the night. As such, the optical switch preferably deactivates the device when the light intensity level falls below a preselected threshold limit e.g. below about 100 lux. In a preferred embodiment, the optical switch deactivates the device when the light intensity level is about 10 lux or less. It may be possible to vary the preselected threshold limit.
In a preferred embodiment, the device is carried by the subject animal via attachment means e.g. a collar, which includes light emitting or reflecting markings to provide a visual warning of the subject animals presence in addition to the sonic warning emitted by the device. Since birds for example can detect light in the UV region of the electromagnetic spectrum, the markings preferably emit and/or reflect UV light.
The sonic emissions of the device may interfere with the natural interactions between two or more subject animals e.g. during mating. To overcome any such unwanted interference, the device may include a proximity sensor which is capable of temporarily deactivating the device when it detects another such device in close proximity to it. That is to say when two subject animals both of which are wearing sonic devices are in close proximity to each other, both of the devices may be temporarily deactivated.
A second aspect of the present invention provides a method of reducing predation by a subject animal, the method including fitting the subject animal with a device according to the first aspect of the invention. Preferably, the device is fitted via attachment means, more preferably via a collar.
A third aspect of the present invention provides use of a sonic device according to the first aspect of the invention to alert prey to the presence of a subject animal.
A fourth aspect of the invention provides an attachment means for wearing by an animal, the attachment means carrying a device according to the first aspect of the invention.
A fifth aspect of the invention provides an animal wearing a device according to the first aspect of the invention. Preferably the device is carried by an attachment means.